Flying, vigilance, indestructible
Other permanents you control have indestructible.

Ward
Whenever you attack, look at the top six cards of your library. You may cast a spell from among them with mana value less than or equal to the greatest power among attacking creatures you control without paying its mana cost. Put the rest on the bottom of your library in a random order.

Whenever an opponent casts a noncreature spell, create a Food token. (It's an artifact with ", , Sacrifice this token: You gain 3 life.")
Whenever a creature deals combat damage to you, sacrifice a Food token.
Tap two untapped Foods you control: Add one mana of any color.

(: Add or .)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

For each creature token on the battlefield, its controller creates a token that's a copy of that creature.
Flashback (You may cast this card from your graveyard for its flashback cost. Then exile it.)

When this creature enters, you take the initiative.
Whenever you attack, target attacking Cleric, Rogue, Warrior, or Wizard gains protection from creatures until end of turn. It explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on the creature, then put the card back or put it into your graveyard.)

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
: Target Merfolk you control gains protection from the color of your choice until end of turn.

Look at the top five cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.

The first creature spell you cast each turn costs less to cast.
Whenever an opponent casts their first noncreature spell each turn, this enchantment deals 2 damage to that player.

When this creature enters, you may search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

Horsemanship (This creature can't be blocked except by creatures with horsemanship.)
Whenever this creature deals damage to an opponent, that player discards a card.

: Draw a card and reveal it. If it isn't a land card, discard it.

: Add .
, , Sacrifice this land: Destroy target nonbasic land an opponent controls. Each player searches their library for a basic land card, puts it onto the battlefield, then shuffles.

Flying
Whenever this creature deals combat damage to a player, that player gets two rad counters if they don't have any rad counters. Otherwise, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Haste
When this creature enters, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.

: Add .
, Sacrifice a creature: Add .

Sacrifice an artifact: This creature deals 1 damage to each creature without flying.

Vivid — : For each color among permanents you control, add one mana of that color.

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of your end step, exile up to one other target creature you control, then return that card to the battlefield under your control.
: Tap another target creature.

: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.